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Homework Write a program that automatically matches up words with definitions for the 3 quizzes. – Report your results the number your program got right for each quiz – Explain the heuristics you chose – For cases that don’t work, explain why? Is it your algorithm? Is it WordNet? … – Your conclusion: is Wordnet adequate to the task of connecting up the words with the definitions?

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Sample ideas Heuristics – cost = # relations in (a) shortest path bfs3.perl stops when it finds a shortest path – overall lowest cost for the quiz looks at all possible assignments from words to definitions there could be other same lowest cost paths – stopwords prepositions, articles, etc. – multi-word definitions check match for word to all of the non-stopwords discounted cost if multiple matches

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Predicate-Argument Structure It can be difficult to precisely specify the meaning of the arguments via thematic labels of this sort Here is a list of the major thematic relations. Agent : –deliberately performs the action –(e.g. Bill ate his soup quietly) Experiencer : –receives sensory or emotional input –(e.g. The smell of lilies filled Jennifer's nostrils ). Theme : –undergoes the action but does not change its state –(Sometimes used interchangeably with patient) –(e.g. Bill kissed Mary ). Patient: –undergoes the action and has its state changed –(Sometimes used interchangeably with theme) –(e.g. The falling rocks crushed the car ) Instrument : –used to carry out the action –(e.g. Jamie cut the ribbon with a pair of scissors ). Natural Cause : –mindlessly performs the action –(e.g. An avalanche destroyed the ancient temple). Location : –where the action occurs –(e.g. Johnny and Linda played carelessly in the park ). Goal : –what the action is directed towards –(e.g. The caravan continued on toward the distant oasis ). Recipient : –a special kind of goal associated with verbs expressing a change in ownership, possession. –(e.g I sent John the letter) Source : –where the action originated –(e.g. The rocket was launched from Central Command ). Time : –the time at which the action occurs –(e.g. The rocket was launched yesterday ) Beneficiary : –the entity for whose benefit the action occurs –(e.g. I baked Reggie a cake)

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Predicate-Argument Structure Passives – The sandwich was eaten by John – John ate the sandwich – eat(, ) – eat(john,sandwich) – The sandwich was eaten – eat(_,sandwich) – an incomplete or underspecified predicate argument structure Not all Noun Phrases seem to have a meaningful thematic relation associated with them – It rains – It is likely that John ate the sandwich – John is likely to eat the sandwich – It seems that John ate the sandwich – John seemed to eat the sandwich – There seems to be a sandwich over there – A sandwich seems to be over there